U.S. patent number 9,156,215 [Application Number 13/309,654] was granted by the patent office on 2015-10-13 for method for making silicone hydrogel contact lenses.
This patent grant is currently assigned to Novartis AG. The grantee listed for this patent is Angelika Maria Domschke, Uwe Haken, Horngyih Huang, Yasuo Matsuzawa, John Dallas Pruitt, Newton T. Samuel, Daqing Wu. Invention is credited to Angelika Maria Domschke, Uwe Haken, Horngyih Huang, Yasuo Matsuzawa, John Dallas Pruitt, Newton T. Samuel, Daqing Wu.
United States Patent |
9,156,215 |
Samuel , et al. |
October 13, 2015 |
Method for making silicone hydrogel contact lenses
Abstract
The invention provides a method for washing, with a water-based
system, reusable molds for making silicone hydrogel contact lenses.
The water-based washing system comprises an ethoxylated silicone
polyether surfactant. The water-based system of the invention can
effectively wash away silicone-containing components and other
components of a lens formulation left behind on the molding
surfaces of a reusable mold, after removing a silicone hydrogel
contact lens cast molded in the reusable mold.
Inventors: |
Samuel; Newton T. (Suwanee,
GA), Huang; Horngyih (Alpharetta, GA), Wu; Daqing
(Suwanee, GA), Haken; Uwe (Norcross, GA), Pruitt; John
Dallas (Suwanee, GA), Domschke; Angelika Maria (Duluth,
GA), Matsuzawa; Yasuo (Roswell, GA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samuel; Newton T.
Huang; Horngyih
Wu; Daqing
Haken; Uwe
Pruitt; John Dallas
Domschke; Angelika Maria
Matsuzawa; Yasuo |
Suwanee
Alpharetta
Suwanee
Norcross
Suwanee
Duluth
Roswell |
GA
GA
GA
GA
GA
GA
GA |
US
US
US
US
US
US
US |
|
|
Assignee: |
Novartis AG (Basel,
CH)
|
Family
ID: |
45349587 |
Appl.
No.: |
13/309,654 |
Filed: |
December 2, 2011 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20120139138 A1 |
Jun 7, 2012 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61420077 |
Dec 6, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B
1/043 (20130101); B08B 9/00 (20130101); B29D
11/00153 (20130101); G02B 1/043 (20130101); C08L
83/04 (20130101); G02B 1/043 (20130101); C08L
101/14 (20130101) |
Current International
Class: |
B29D
11/00 (20060101); G02B 1/04 (20060101) |
Field of
Search: |
;264/1.1,1.26,1.38,2.5,2.6 ;425/808 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
PCT International Search Report dated Feb. 15, 2012, International
Application No. PCT/US2011/062986, International Filing Date Dec.
2, 2011. cited by applicant .
PCT Written Opinion of the International Searching Authority dated
Feb. 15, 2012, International Application No. PCT/US2011/062986,
International Filing Date Dec. 2, 2011. cited by applicant.
|
Primary Examiner: Vargot; Mathieu
Attorney, Agent or Firm: Zhou; Jian
Parent Case Text
This application claims the benefit under 35 USC .sctn.119 (e) of
U.S. provisional application No. 61/420,077 filed Dec. 6, 2010,
incorporated herein by reference in its entirety.
The present invention is related to a method for making silicone
hydrogel contact lenses, in particular, a method for in-line
cleaning of reusable molds for making silicone hydrogel contact
lenses under spatial limitation of actinic radiation.
Claims
What is claimed is:
1. A method for producing silicone hydrogel contact lenses,
comprising the steps of: (1) providing a reusable mold for making
soft contact lenses, wherein the mold has a first mold half with a
first molding surface defining the anterior surface of a contact
lens and a second mold half with a second molding surface defining
the posterior surface of the contact lens, wherein said first and
second mold halves are configured to receive each other such that a
cavity is formed between said first and second molding surfaces;
(2) introduce a fluid polymerizable composition into the cavity,
wherein the fluid polymerizable composition comprises at least one
silicone-containing lens-forming material selected from the group
consisting of a siloxane-containing vinylic monomer, a
polysiloxane-containing vinylic monomer, a polysiloxane-containing
macromer, a polysiloxane-containing crosslinker, an
actinically-crosslinkable silicone-containing prepolymer, and a
mixture thereof; (3) irradiating, under a spatial limitation of
actinic radiation, the fluid composition in the mold for a time
period of about 200 seconds or less, so as to form a silicone
hydrogel contact lens, wherein the formed silicone hydrogel contact
lens comprises an anterior surface defined by the first molding
surface, an opposite posterior surface defined by the second
molding surface, and a lens edge defined by the spatial limitation
of actinic radiation; (4) opening the mold and removing the formed
silicone hydrogel contact lens from the mold; (5) removing the
silicone-containing lens forming material and other components of
the fluid composition left behind on the first and second molding
surfaces of the mold by washing the first and second molding
surfaces of the reusable mold with a water-based solution
containing from about 0.01% to about 2.5% by weight of a silicone
surfactant, wherein the silicone surfactant is an ethoxylated
water-soluble polyether; and (6) repeating the steps (2) to
(5).
2. The method of claim 1, wherein the ethoxylated water-soluble
silicone polyether is a linear block copolymer of polyethylenglycol
with polydimethylsiloxane of formula (1), a pendant
polyethylenglycol dimethicone of formula (2), or a silicone glycol
of formula (3) ##STR00005## In which: R.sub.3, R.sub.4, R.sub.5,
R.sub.6, R.sub.7, R.sub.8, R.sub.11, R.sub.12, R.sub.13, R.sub.14,
R.sub.15, R.sub.18, R.sub.19, R.sub.20, R.sub.21, R.sub.22,
R.sub.23, R.sub.25, and R.sub.26, independent of one another are
CH.sub.3 or CH.sub.2CH.sub.3; R.sub.9 and R.sub.10 independent of
each other are a monovalent radical of ##STR00006## in which p1 is
an integer of 6 to 12, and p2 is 0 to 8; R.sub.16, and R.sub.24
independent of one another are divalent radical of
--(CH.sub.2).sub.a-- in which a is an integer of 1 to 5; R.sub.17
is CH.sub.3 or a monovalent radical of --(CH.sub.2).sub.b--CH.sub.3
in which b is an integer from 9 to 15; p1 is an integer of 6 to 12,
and p2 is 0 to 8; m is an integer of 4 to 20; u is an integer of 1
to 5; q and r independent of each another are an integer of 2-10,
provided that r/q is equal to or larger than 1 and that t is zero
or an integer of (q+r) time x which is 1.5 to 2.5.
3. The method of claim 2, wherein the water-based solution further
comprises an effective amount of a defoaming agent.
4. The method of claim 3, wherein the defoaming agent comprises
finely powdered silica having a particle size of about 5 microns or
less.
5. The method of claim 3, wherein the fluid polymerizable
composition comprises a siloxane-containing vinylic monomer and a
polysiloxane-containing vinylic monomer or macromer or
crosslinker.
6. The method of claim 3, wherein the siloxane-containing vinylic
monomer is N-[tris(trimethylsiloxy)silylpropyl](meth)acrylamide,
N-[tris(dimethylpropylsiloxy)silylpropyl](meth)acrylamide,
N-[tris(dimethylphenylsiloxy)silylpropyl]acrylamide,
N-[tris(dimethylphenylsiloxy)silylpropyl](meth)acrylamide,
N-[tris(dimethylethylsiloxy)silylpropyl](meth)acrylamide,
N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)-2-
methyl acrylamide;
N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)
acrylamide;
N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propy-
l]-2-methyl acrylamide;
N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propy-
l]acrylamide;
N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)-2-methy-
l acrylamide;
N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)acrylami-
de;
N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]-
-2-methyl acrylamide;
N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]acr-
ylamide;
N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methy-
l acrylamide;
N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;
N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methyl
acrylamide;
N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;
3-methacryloxy propylpentamethyldisiloxane,
tris(trimethylsilyloxy)silylpropyl methacrylate (TRIS),
(3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane-
),
(3-methacryloxy-2-hydroxypropyloxy)propyltris(trimethylsiloxy)silane,
3-methacryloxy-2-(2-hydroxyethoxy)-propyloxy)propylbis(trimethylsiloxy)me-
thylsilane,
N-2-methacryloxyethyl-O-(methyl-bis-trimethylsiloxy-3-propyl)silyl
carbamate, 3-(trimethylsilyl)propylvinyl carbonate,
3-(vinyloxycarbonylthio)propyl-tris(trimethyl -siloxy)silane,
3-[tris(trimethylsiloxy)silyl]propylvinyl carbamate,
3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate,
3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate,
t-butyldimethyl-siloxyethyl vinyl carbonate; trimethylsilylethyl
vinyl carbonate, trimethylsilylmethyl vinyl carbonate), or
combinations thereof.
7. The method of claim 3, wherein the siloxane-containing vinylic
monomer is N-[tris(trimethylsiloxy)silylpropyl](meth)acrylamide,
tris(trimethylsilyloxy)silylpropyl methacrylate,
3-methacryloxy-2-hydroxypropyloxy)propyl-bis(trimethylsiloxy)methylsilane-
, or combinations thereof.
8. The method of claim 3, wherein the fluid polymerizable
composition comprises an actinically-crosslinkable
silicone-containing prepolymer.
9. The method of claim 3, wherein at least one of the first and
second molding surfaces is permeable to a crosslinking
radiation.
10. The method of claim 9, wherein the reusable mold comprises a
mask which is fixed on the mold half having the radiation-permeable
molding surface.
11. The method of claim 10, wherein the fluid polymerizable
composition comprises a hydrophilic vinylic monomer selected from
the group consisting of N,N-dimethylacrylamide,
N,N-dimethylmethacrylamide, 2-acrylamidoglycolic acid,
3-acryloylamino-1-propanol, N-hydroxyethyl acrylamide,
N-[tris(hydroxymethyl)methyl]-acrylamide,
N-methyl-3-methylene-2-pyrrolidone,
1-ethyl-3-methylene-2-pyrrolidone,
1-methyl-5-methylene-2-pyrrolidone,
1-ethyl-5-methylene-2-pyrrolidone,
5-methyl-3-methylene-2-pyrrolidone,
5-ethyl-3-methylene-2-pyrrolidone,
1-n-propyl-3-methylene-2-pyrrolidone,
1-n-propyl-5-methylene-2-pyrrolidone,
1-isopropyl-3-methylene-2-pyrrolidone,
1-isopropyl-5-methylene-2-pyrrolidone,
1-n-butyl-3-methylene-2-pyrrolidone,
1-tert-butyl-3-methylene-2-pyrrolidone, 2-hydroxyethylmethacrylate,
2-hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxypropyl
methacrylate, trimethylammonium 2-hydroxy propylmethacrylate
hydrochloride, aminopropyl methacrylate hydrochloride,
dimethylaminoethyl methacrylate, glycerol methacrylate,
N-vinyl-2-pyrrolidone, allyl alcohol, vinylpyridine, a
C.sub.1-C.sub.4-alkoxy polyethylene glycol (meth)acrylate having a
weight average molecular weight of up to 1500, methacrylic acid,
N-vinyl formamide, N-vinyl acetamide, N-vinyl isopropylamide,
N-vinyl-N-methyl acetamide, N-vinyl caprolactam, and mixtures
thereof.
12. The method of claim 11, wherein the fluid polymerizable
composition comprises one or more hydrophobic comfort agents
selected from the group consisting of phospholipid, monoglyceride,
diglyceride, triglyceride, glycolipid, glyceroglycolipid,
sphingolipid, sphingo-glycolipid, fatty alcohol, hydrocarbon having
a C.sub.12-C.sub.28 chain in length, wax ester, fatty acid, mineral
oil, silicone oil, and combinations thereof.
13. The method of claim 12, wherein the hydrophobic comfort agents
comprises a phospholipid.
14. The method of claim 11, wherein the fluid polymerizable
composition comprises polyglycolic acid and/or a non-crosllinkable
hydrophilic polymer having a weight-average molecular weight
M.sub.w of from 5,000 to 1,500,000 Daltons.
15. The method of claim 11, wherein the fluid polymerizable
composition comprises a bioactive agent selected from the group
consisting of rebamipide, ketotifen, olaptidine, cromoglycolate,
cyclosporine, nedocromil, levocabastine, lodoxamide, ketotifen,
2-pyrrolidone-5-carboxylic acid glycolic acid, lactic acid, malic
acid, tartaric acid, mandelic acid, citric acids, linoleic acid,
gamma linoleic acid, vitamins, and combinations thereof.
Description
BACKGROUND
In recent years, soft silicone hydrogel contact lenses become more
and more popular because of their high oxygen permeability and
comfort. However, all commercially available silicone hydrogel
contact lenses are produced according to a conventional cast
molding technique involving use of disposable plastic molds and a
mixture of monomers in the presence or absence of macromers.
However, disposable plastic molds inherently have unavoidable
dimensional variations, because, during injection-molding of
plastic molds, fluctuations in the dimensions of molds can occur as
a result of fluctuations in the production process (temperatures,
pressures, material properties), and also because the resultant
molds may undergo non-uniformly shrinking after the injection
molding. These dimensional changes in the mold may lead to
fluctuations in the parameters of contact lenses to be produced
(peak refractive index, diameter, basic curve, central thickness
etc.) and to a low fidelity in duplicating complex lens design.
Such disadvantages encountered in a conventional cast-molding
technique can be overcome by using the so-called Lightstream
Technology.TM. (CIBA Vision), as illustrated in U.S. Pat. Nos.
5,508,317, 5,789,464, 5,849,810, and 6,800,225, which are
incorporated by reference in their entireties. The Lightstream
Technology.TM. involves (1) a lens-forming composition which is
typically a solution of one or more substantially purified
prepolymer with ethylenically unsaturated groups and which
generally is substantially free of monomers and crosslinking agents
with a small molecular weight, (2) reusable molds produced in high
precision, (3) curing under a spatial limitation of actinic
radiation (e.g., UV); and washing and reusing the reusable molds.
Lenses produced according to the Lightstream Technology.TM. can
have high consistency and high fidelity to the original lens
design, because of use of reusable, high precision molds. In
addition, contact lenses with high quality can be produced at
relatively lower cost due to the short curing time and a high
production yield.
But, the Lightstream Technology.TM. has not been applied to make
silicone hydrogel contact lenses. One potential issue in the
manufacture of silicone hydrogel contact lenses based on
Lightstream Technology.TM. is that the silicone-containing
components of a lens formulation left behind on the mold surface
may not be water soluble and an organic solvent may have to be used
to wash the reusable molds. However, use of organic solvents can be
costly and is not environmentally friendly. A water-based mold
washing system is desirable. Therefore, there is still a need for a
method for washing, with a water-based system, reusable molds for
making silicone hydrogel contact lenses according to the
Lightstream Technology.TM..
SUMMARY OF THE INVENTION
In one aspect, the invention provides a method for producing
silicone hydrogel contact lenses, involving use of a reusable mold
for cast-molding silicone hydrogel contact lenses and a step of
cleaning/washing the reusable mold with a water-based solution
containing a silicone surfactant which is an ethoxylated
water-soluble silicone polyether.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Unless defined otherwise, all technical and scientific terms used
herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs.
Generally, the nomenclature used herein and the laboratory
procedures are well known and commonly employed in the art.
Conventional methods are used for these procedures, such as those
provided in the art and various general references. Where a term is
provided in the singular, the inventors also contemplate the plural
of that term. The nomenclature used herein and the laboratory
procedures described below are those well known and commonly
employed in the art.
"Contact Lens" refers to a structure that can be placed on or
within a wearer's eye. A contact lens can correct, improve, or
alter a user's eyesight, but that need not be the case. A contact
lens can be of any appropriate material known in the art or later
developed, and can be a soft lens, a hard lens, or a hybrid lens. A
"silicone hydrogel contact lens" refers to a contact lens
comprising a silicone hydrogel material.
A "hydrogel" or "hydrogel material" refers to a polymeric material
which can absorb at least 10 percent by weight of water when it is
fully hydrated.
A "silicone hydrogel" refers to a silicone-containing hydrogel
obtained by copolymerization of a polymerizable composition
comprising at least one silicone-containing monomer or at least one
silicone-containing macromer or at least one crosslinkable
silicone-containing prepolymer.
"Hydrophilic," as used herein, describes a material or portion
thereof that will more readily associate with water than with
lipids.
A "vinylic monomer" refers to a low molecular weight compound that
has one sole ethylenically unsaturated group. Low molecular weight
typically means average molecular weights less than 700
Daltons.
The term "olefinically unsaturated group" or "ethylenicaly
unsaturated group" is employed herein in a broad sense and is
intended to encompass any groups containing a >C.dbd.C<
group. Exemplary ethylenically unsaturated groups include without
limitation acryloyl, methacryloyl, allyl, vinyl, styrenyl, or other
C.dbd.C containing groups.
The term "(meth)acrylamide" refers to methacrylamide and/or
acrylamide.
The term "(meth)acrylate" refers to methacrylate and/or
acrylate.
As used herein, "actinically" in reference to curing, crosslinking
or polymerizing of a polymerizable composition, a prepolymer or a
material means that the curing (e.g., crosslinked and/or
polymerized) is performed by actinic irradiation, such as, for
example, UV irradiation, ionizing radiation (e.g. gamma ray or
X-ray irradiation), microwave irradiation, and the like. Thermal
curing or actinic curing methods are well-known to a person skilled
in the art.
A "polysiloxane-containing vinylic monomer or macromer" refers to a
vinylic monomer or macromer containing one sole ethylenically
unsaturated group and a divalent radical of linear segment
##STR00001## in which R.sub.1 and R.sub.2 are independently a
monovalent C.sub.1-C.sub.10 alkyl, a monovalent C.sub.1-C.sub.10
aminoalkyl, a monovalent of C.sub.1-C.sub.10 hydroxyalkyl,
C.sub.1-C.sub.10 ether, C.sub.1-C.sub.10 fluoroalkyl,
C.sub.1-C.sub.10 fluoroether or C.sub.6-C.sub.18 aryl radical,
-alk-(OCH.sub.2CH.sub.2).sub.m--OR.sub.3, in which alk is
C.sub.1-C.sub.6 alkylene divalent radical, R.sub.3 is hydrogen or
C.sub.1-C.sub.6 alkyl, and m is an integer of from 1 to 10; n is an
integer of 2 or higher.
A "siloxane-containing vinylic monomer" refers to a vinylic monomer
that comprises one sole ethylenically-unsaturated group and a
radical of
##STR00002## in which A.sub.1, A.sub.2 and A.sub.3 independent of
each other are C.sub.1-C.sub.12 alkyl which is linear or branched
and optionally substituted or terminated with C1-C4 alkoxy,
hydroxyl, or amino group, phenyl, or benzyl.
The term "fluid" as used herein indicates that a material is
capable of flowing like a liquid.
A "hydrophilic vinylic monomer", as used herein, refers to a
vinylic monomer which as a homopolymer typically yields a polymer
that is water-soluble or can absorb at least 10 percent by weight
water.
A "hydrophobic vinylic monomer", as used herein, refers to a
vinylic monomer which as a homopolymer typically yields a polymer
that is insoluble in water and can absorb less than 10 percent by
weight water.
A "vinylic macromer" refers to a medium and high molecular weight
compound which comprises one sole ethylenically unsaturated groups.
Medium and high molecular weight typically means average molecular
weights greater than 700 Daltons.
A "prepolymer" refers to a starting polymer which contains two or
more ethylenically unsaturated groups and can be cured (e.g.,
crosslinked) actinically to obtain a crosslinked polymer having a
molecular weight much higher than the starting polymer.
A "silicone-containing prepolymer" refers to a prepolymer which
contains silicone.
A "crosslinker" refers to a compound having at least two
ethylenically-unsaturated groups. A "crossliking agent" refers to a
compound which belongs to a subclass of crosslinkers and comprises
at least two ethylenically unsaturated groups and has a molecular
weight of 700 Daltons or less.
"Molecular weight" of a polymeric material (including monomeric or
macromeric materials), as used herein, refers to the weight-average
molecular weight unless otherwise specifically noted or unless
testing conditions indicate otherwise.
"Polymer" means a material formed by polymerizing one or more
monomers.
As used herein, the term "ethylenically functionalized" in
reference to a copolymer or a compound is intended to describe that
one or more actinically crosslinkable groups have been covalently
attached to a copolymer or compound through the pendant or terminal
functional groups of the copolymer or the compound according to a
coupling process.
As used herein, the term "multiple" refers to three or more.
A "spatial limitation of actinic radiation" refers to an act or
process in which energy radiation in the form of rays is directed
by, for example, a mask or screen or combinations thereof, to
impinge, in a spatially restricted manner, onto an area having a
well defined peripheral boundary. A spatial limitation of UV
radiation is obtained by using a mask or screen having a radiation
(e.g.,UV) permeable region, a radiation (e.g., UV) impermeable
region surrounding the radiation-permeable region, and a projection
contour which is the boundary between the radiation-impermeable and
radiation-permeable regions, as schematically illustrated in the
drawings of U.S. Pat. No. 6,800,225 (FIGS. 1-11), and U.S. Pat. No.
6,627,124 (FIGS. 1-9), U.S. Pat. No. 7,384,590 (FIGS. 1-6), and
U.S. Pat. No. 7,387,759 (FIGS. 1-6), all of which are incorporated
by reference in their entireties. The mask or screen allows to
spatially projects a beam of radiation (e.g., UV radiation) having
a cross-sectional profile defined by the projection contour of the
mask or screen. The projected beam of radiation (e.g., UV
radiation) limits radiation (e.g., UV radiation) impinging on a
lens-forming material located in the path of the projected beam
from the first molding surface to the second molding surface of a
mold. The resultant contact lens comprises an anterior surface
defined by the first molding surface, an opposite posterior surface
defined by the second molding surface, and a lens edge defined by
the sectional profile of the projected UV beam (i.e., a spatial
limitation of radiation). The radiation used for the crosslinking
is a radiation energy, especially UV radiation, gamma radiation,
electron radiation or thermal radiation, the radiation energy
preferably being in the form of a substantially parallel beam in
order on the one hand to achieve good restriction and on the other
hand efficient use of the energy.
In the conventional cast-molding process, the first and second
molding surface of a mold are pressed against each other to form a
circumferential contact line which defines the edge of a result
contact lens. Because the close contact of the molding surfaces can
damage the optical quality of the molding surfaces, the mold cannot
be reused. In contrast, in the Lightstream Technology.TM., the edge
of a resultant contact lens is not defined by the contact of the
molding surfaces of a mold, but instead by a spatial limitation of
radiation. Without any contact between the molding surfaces of a
mold, the mold can be used repeatedly to produce high quality
contact lenses with high reproducibility.
In general, the invention is directed to a method for making
silicone hydrogel contact lenses based on the Lightstream
Technology.TM.. The invention is partly based on the discovery that
ethoxylated water-soluble silicone polyethers can be used as a
surfactant in a water-based solution to effectively clean/wash
resuable molds involved in cast-molding of silicone hydrogel
contact lenses. It is believed that an ethoxylated silicone
polyether can facilitate the dissolution of silicone-containing
components of a silicone hydrogel lens formulation in water and/or
fine dispersion of such silicone-containing component in water.
The invention provides a method for producing silicone hydrogel
contact lenses. The method comprises the steps of: (1) providing a
reusable mold for making soft contact lenses, wherein the mold has
a first mold half with a first molding surface defining the
anterior surface of a contact lens and a second mold half with a
second molding surface defining the posterior surface of the
contact lens, wherein said first and second mold halves are
configured to receive each other such that a cavity is formed
between said first and second molding surfaces; (2) introduce a
fluid polymerizable composition into the cavity, wherein the fluid
polymerizable composition comprises at least one
silicone-containing lens-forming material selected from the group
consisting of a siloxane-containing vinylic monomer, a
polysiloxane-containing vinylic monomer, a polysiloxane-containing
macromer, a polysiloxane-containing crosslinker, an
actinically-crosslinkable silicone-containing prepolymer, and a
mixture thereof; (3) irradiating, under a spatial limitation of
actinic radiation, the fluid composition in the mold for a time
period of about 200 seconds or less, so as to form a silicone
hydrogel contact lens, wherein the formed silicone hydrogel contact
lens comprises an anterior surface defined by the first molding
surface, an opposite posterior surface defined by the second
molding surface, and a lens edge defined by the spatial limitation
of actinic radiation; (4) opening the mold and removing the formed
silicone hydrogel contact lens from the mold; (5) removing the
silicone-containing lens forming material and other components of
the fluid composition left behind on the first and second molding
surfaces of the mold by washing the first and second molding
surfaces of the reusable mold with a water-based solution
containing from about 0.01% to about 2.5% by weight of a silicone
surfactant, wherein the silicone surfactant is an ethoxylated
water-soluble silicone polyether; and (6) repeating the steps (2)
to (5).
Examples of reusable molds suitable for spatial limitation of
radiation include without limitation those disclosed in U.S. Pat.
Nos. 6,800,225, 6,627,124, 7,384,590, and 7,387,759, which are
incorporated by reference in their entireties.
For example, a preferred reusable mold comprises a first mold half
having a first molding surface and a second mold half having a
second molding surface. The two mold halves of the preferred
reusable mold are not touching each other, but there is a thin gap
of annular design arranged between the two mold halves. The gap is
connected to the mold cavity formed between the first and second
molding surfaces, so that excess monomer mixture can flow into the
gap. It is understood that gaps with any design can be used in the
invention.
In a preferred embodiment, at least one of the first and second
molding surfaces is permeable to a crosslinking radiation, e.g., UV
radiation). More preferably, one of the first and second molding
surfaces is permeable to a crosslinking radiation (e.g., UV
radiation) while the other molding surface is poorly permeable to
the crosslinking radiation (e.g., UV radiation). For example, one
of the mold halves can be made of a UV-permeable material, while
the other mold half can be made of a material containing UV
absorbing materials, such as, for example carbon black, as
described in U.S. Pat. Nos. 7,387,759 and 7,384,590.
The reusable mold preferably comprises a mask which is fixed,
constructed or arranged in, at or on the mold half having the
radiation-permeable molding surface. The mask is impermeable or at
least of poor permeability compared with the permeability of the
radiation-permeable molding surface. The mask extends inwardly
right up to the mold cavity and surrounds the mold cavity so as to
screen all areas behind the mask with the exception of the mold
cavity.
Where the curing radiation is UV light, the mask may preferably be
a thin chromium layer, which can be produced according to processes
as known, for example, in photo and UV lithography. Other metals or
metal oxides may also be suitable mask materials. The mask can also
be coated with a protective layer, for example of silicon dioxide
if the material used for the mould or mould half is quartz.
Alternatively, the mask can be a masking collar made of a material
comprising a UV-absorber and substantially blocks curing energy
therethrough as described in U.S. Pat. No. 7,387,759 (incorporated
by reference in its entirety). In this preferred embodiment, the
mold half with the mask comprises a generally circular disc-shaped
transmissive portion and a masking collar having an inner diameter
adapted to fit in close engagement with the transmissive portion,
wherein said transmissive portion is made from an optically clear
material and allows passage of curing energy therethrough, and
wherein the masking collar is made from a material comprising a
UV-blocker and substantially blocks passage of curing energy
therethrough, wherein the masking collar generally resembles a
washer or a doughnut, with a center hole for receiving the
transmissive portion, wherein the transmissive portion is pressed
into the center opening of the masking collar and the masking
collar is mounted within a bushing sleeve.
Reusable molds can be made of quartz, glass, sapphire, CaF.sub.2, a
cyclic olefin copolymer (such as for example, Topas.RTM. COC grade
8007-S10 (clear amorphous copolymer of ethylene and norbornene)
from Ticona GmbH of Frankfurt, Germany and Summit, N. J.,
Zeonex.RTM. and Zeonor.RTM. from Zeon Chemicals LP, Louisville,
Ky.), polymethylmethacrylate (PMMA), polyoxymethylene from DuPont
(Delrin), Ultem.RTM. (polyetherimide) from G.E. Plastics,
PrimoSpire.RTM., etc. Because of the reusability of the mold
halves, a relatively high outlay can be expended at the time of
their production in order to obtain molds of extremely high
precision and reproducibility. Since the mold halves do not touch
each other in the region of the lens to be produced, i.e. the
cavity or actual molding surfaces, damage as a result of contact is
ruled out. This ensures a high service life of the molds, which, in
particular, also ensures high reproducibility of the contact lenses
to be produced and high fidelity to the lens design.
Any suitable siloxane-containing vinylic monomers can be used in
the invention. Examples of preferred siloxane-containing vinylic
monomers include without limitation
N-[tris(trimethylsiloxy)silylpropyl](meth)acrylamide,
N-[tris(dimethylpropylsiloxy)silylpropyl](meth)acrylamide,
N-[tris(dimethylphenylsiloxy)silylpropyl]acrylamide,
N-[tris(dimethylphenylsiloxy)silylpropyl](meth)acrylamide,
N-[tris(dimethylethylsiloxy)silylpropyl](meth)acrylamide,
N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)-2--
methyl acrylamide;
N-(2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propyl)
acrylamide;
N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propy-
l]-2-methyl acrylamide;
N,N-bis[2-hydroxy-3-(3-(bis(trimethylsilyloxy)methylsilyl)propyloxy)propy-
l]acrylamide;
N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)-2-methy-
l acrylamide;
N-(2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl)acrylami-
de;
N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]-
-2-methyl acrylamide;
N,N-bis[2-hydroxy-3-(3-(tris(trimethylsilyloxy)silyl)propyloxy)propyl]acr-
ylamide;
N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methy-
l acrylamide;
N-[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;
N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]-2-methyl
acrylamide;
N,N-bis[2-hydroxy-3-(3-(t-butyldimethylsilyl)propyloxy)propyl]acrylamide;
3-methacryloxy propylpentamethyldisiloxane,
tris(trimethylsilyloxy)silylpropyl(meth)acrylate,
(3-methacryloxy-2-hydroxypropyloxy)propylbis(trimethylsiloxy)methylsilane-
),
(3-methacryloxy-2-hydroxypropyloxy)propyltris(trimethylsiloxy)silane,
3-methacryloxy-2-(2-hydroxyethoxy)-propyloxy)propylbis(trimethylsiloxy)me-
thylsilane,
N-2-methacryloxyethyl-O-(methyl-bis-trimethylsiloxy-3-propyl)silyl
carbamate, 3-(trimethylsilyl)propylvinyl carbonate,
3-(vinyloxycarbonylthio)propyl-tris(trimethyl-siloxy)silane,
3-[tris(trimethylsiloxy)silyl]propylvinyl carbamate,
3-[tris(trimethylsiloxy)silyl]propyl allyl carbamate,
3-[tris(trimethylsiloxy)silyl]propyl vinyl carbonate,
t-butyldimethyl-siloxyethyl vinyl carbonate; trimethylsilylethyl
vinyl carbonate, trimethylsilylmethyl vinyl carbonate; and
combinations thereof. Most preferred siloxane-containing
(meth)acrylamide monomers are
N-[tris(trimethylsiloxy)silylpropyl]acrylamide,
tris(trimethylsilyloxy)silylpropyl(meth)acrylate,
N-[tris(trimethylsiloxy)silylpropyl](meth)acrylamide,
3-methacryloxy-2-hydroxypropyloxy)propyl-bis(trimethylsiloxy)methylsilane-
, or combinations thereof.
Any suitable polysiloxane-containing vinylic macromers and
crosslinkers can be used in the invention. Examples of preferred
polysiloxane-containing vinylic monomers or macromers and
polysiloxane-containing crosslinkers include without limitation
mono-(meth)acrylate-terminated polydimethylsiloxanes of various
molecular weight (e.g., mono-3-methacryloxypropyl terminated,
mono-butyl terminated polydimethylsiloxane or
mono-(3-methacryloxy-2-hydroxypropyloxy)propyl terminated,
mono-butyl terminated polydimethylsiloxane); mono-vinyl-terminated,
mono-vinyl carbonate-terminated or mono-vinyl carbamate-terminated
polydimethylsiloxanes of various molecular weight;
di-(meth)acrylated polydimethylsiloxanes (or so called polysiloxane
crosslinkers) of various molecular weight; di-vinyl
carbonate-terminated polydimethylsiloxanes (polysiloxane
crosslinkers); di-vinyl carbamate-terminated polydimethylsiloxane
(polysiloxane crosslinkers); di-vinyl terminated
polydimethylsiloxanes (polysiloxane crosslinkers);
di-(meth)acrylamide-terminated polydimethylsiloxanes (polysiloxane
crosslinkers); bis-3-methacryloxy-2-hydroxypropyloxypropyl
polydimethylsiloxane (polysiloxane crosslinker);
N,N,N',N'-tetrakis(3-methacryloxy-2-hydroxypropyl)-alpha,
omega-bis-3-aminopropyl-polydimethylsiloxane (polysiloxane
crosslinkers); polysiloxanylalkyl(meth)acrylic monomers; the
reaction products of glycidyl methacrylate with amino-functional
polydimethylsiloxanes; hydroxyl-containing polysiloxane vinylic
monomers or crosslinkerss; polysiloxane-containing macromer
selected from the group consisting of Macromer A, Macromer B,
Macromer C, and Macromer D described in U.S. Pat. No. 5,760,100
(herein incorporated by reference in its entirety); the reaction
products of glycidyl methacrylate with amino-functional
polydimethylsiloxanes; hydroxyl-functionalized siloxane-containing
vinylic monomers or macromers; polysiloxane-containing macromers
disclosed in U.S. Pat. Nos. 4,136,250, 4,153,641, 4,182,822,
4,189,546, 4,343,927, 4,254,248, 4,355,147, 4,276,402, 4,327,203,
4,341,889, 4,486,577, 4,543,398, 4,605,712, 4,661,575, 4,684,538,
4,703,097, 4,833,218, 4,837,289, 4,954,586, 4,954,587, 5,010,141,
5,034,461, 5,070,170, 5,079,319, 5,039,761, 5,346,946, 5,358,995,
5,387,632, 5,416,132, 5,451,617, 5,486,579, 5,962,548, 5,981,675,
6,039,913, and 6,762,264 (here incorporated by reference in their
entireties); polysiloxane-containing macromers disclosed in U.S.
Pat. Nos. 4,259,467, 4,260,725, and 4,261,875 (herein incorporated
by reference in their entireties). Di and triblock macromers
consisting of polydimethylsiloxane and polyalkyleneoxides could
also be of utility. For example one might use methacrylate end
capped
polyethyleneoxide-block-polydimethylsiloxane-block-polyethyleneoxide
to enhance oxygen permeability. Suitable monofunctional
hydroxyl-functionalized siloxane-containing vinylic
monomers/macromers and suitable multifunctional
hydroxyl-functionalized siloxane-containing vinylic
monomers/macromers are commercially available from Gelest, Inc,
Morrisville, Pa.
A polysiloxane-containing vinylic macromer can be prepared
according to any known procedures, for example, those described in
U.S. Pat. Nos. 4,136,250, 4,486,577, 4,605,712, 5,034,461,
5,416,132, and 5,760,100, herein incorporated by reference in their
entireties.
Any suitable silicone-containing actinically-crosslinkable
prepolymers can be used in the invention. Examples of preferred
silicone-containing actinically-crosslinkable prepolymers include
without limitation those described in U.S. Pat. Nos. 6,039,913,
7,091,283, 7,268,189 and 7,238,750, and in U.S. patent application
Ser. Nos. 09/525,158, 11/825,961, 12/001,562, 12/001,521,
12/077,772, 12/077,773, which are incorporated herein by references
in their entireties.
Any ethoxylated water-soluble silicone polyethers can be used in
the invention so long as they can facilitate dissolving or
dispersing of both a siloxane-containing vinylic monomer and a
polysiloxane-containing vinylic monomer or macromer or crosslinker
according to the procedures described in Example 2. Preferably, an
ethoxylated water-soluble silicone polyether is a linear block
copolymer of polyethylenglycol (PEG) with polydimethylsiloxane (or
lineal PEG dimethicone) of formula (1), a pendant PEG dimethicone
of formula (2), or a silicone glycol of formula (3)
##STR00003## In which: R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7,
R.sub.8, R.sub.11, R.sub.12, R.sub.13, R.sub.14, R.sub.15,
R.sub.18, R.sub.19, R.sub.20, R.sub.21, R.sub.22, R.sub.23,
R.sub.25, and R.sub.26, independent of one another are CH.sub.3 or
CH.sub.2CH.sub.3, preferably CH.sub.3; R.sub.9 and R.sub.10
independent of each other are a monovalent radical of
##STR00004## in which p1 is an integer of 6 to 12, preferably 8 to
10, more preferably 8, and p2 is 0 to 8; R.sub.16, and R.sub.24
independent of one another are divalent radical of
--(CH.sub.2).sub.a-- in which a is an integer of 1 to 5, preferably
2 or 3, more preferably 3; R.sub.17 is CH.sub.3 or a monovalent
radical of --(CH.sub.2).sub.b--CH.sub.3 in which b is an integer
from 9 to 15, preferably 11 to 13, more preferably 11; p1 is an
integer of 6 to 12, preferably 8 to 10, more preferably 8, and p2
is 0 to 8; m is an integer of 4 to 20; u is an integer of 1 to 5,
preferably 1 to 3, more preferably 1; q and r independent of each
another are an integer of 2-10, provided that r/q is equal to or
larger than 1 and that t is zero or an integer of (q+r) time x
which is 1.5 to 2.5.
Examples of ethoxylated silicone polyether surfactants include
without limitation Silsurf.RTM. Series surfactants (e.g.,
Silsurf.RTM. A208, B208) from Siltech, Silube.RTM. series
surfactants (e.g., Silube.RTM. J-208) from Siltech, Sylgard.RTM.
309 from Dow Corning, and those described in U.S. Pat. Nos.
5,145,977 and 7,279,503 and US patent application publication Nos.
2003/013808 and 2010/0022660 (herein incorporated by references in
their entireties), and combinations thereof. Preferably, an
ethoxylated silicone polyether having a INCI name of PEG-8
Dimethicone is used in the present invention.
Generally, an ethoxylated silicone polyether surfactant has a high
foaming property. Preferably, a water-based solution for
washing/cleaning reusable molds further comprises a defoamer.
Examples of preferred defoamers include without limitation finely
powdered silica, defoaming agents from Shin Etsu (e.g., KM-7750B
which contains silica particles with a medium size of about 2.6
microns as measured, or X-22-1927 which is a silicone base defoamer
and does not contain silica powder), defoaming agent from BASF
(e.g., BASF DF 10P MOD 12 defoamer which is an organic base
defoamer which did not contain any silicon or silica powder),
antifoam agents from Dow Corning, and the like. Preferably, the
defoamer used in the mold cleaning solution is finely powdered
silica having a particle size of about 5 microns or less,
preferably about 4 microns or less, more preferably about 3 microns
or less, even more preferably about 2 microns or less.
In accordance with the invention, an effective amount of a defoamer
is preferably added in a water-based mold cleaning solution. The
term "effective amount" used in this application means that when
the defoamer is present in a given amount in a water-based mold
cleaning solution and the mold cleaning solution is used in a
dispensing tank equipped with re-circulating pump with the pump on
for about 7 minutes and maintained at 40.degree. C. and is spread
on mold surface at a nozzle to mold edge distance of about 1.0 cm
and about 50 psi with a 65.degree. fan spread nozzle with
25.degree. spread angle, a foam height is less than about 5 mm,
preferably about 4 mm or less, more preferably about 3 mm or less,
even more preferably about 2 mm or less.
In accordance with the present invention, a fluid polymerizable
composition can comprise various components as known to a person
skilled in the art, such as, for example, one or more hydrophilic
vinylic monomers, one or more hydrophobic vinylic monomers, a
photoinitiator, one or more cross-linking agents, a UV-absorbing
agent, a visibility tinting agent (e.g., a dye, a pigment, or a
mixture thereof), an antimicrobial agent (e.g., silver
nanoparticles), a bioactive agent, a leachable lubricant, and the
like, as known to a person skilled in the art. a chain transfer
agent,
Any hydrophilic vinylic monomer can be used in the invention.
Examples of preferred hydrophilic vinylic monomers are
N,N-dimethylacrylamide (DMA), N,N-dimethylmethacrylamide (DMMA),
2-acrylamidoglycolic acid, 3-acryloylamino-1-propanol,
N-hydroxyethyl acrylamide,
N-[tris(hydroxymethyl)methyl]-acrylamide,
N-methyl-3-methylene-2-pyrrolidone,
1-ethyl-3-methylene-2-pyrrolidone,
1-methyl-5-methylene-2-pyrrolidone,
1-ethyl-5-methylene-2-pyrrolidone,
5-methyl-3-methylene-2pyrrolidone,
5-ethyl-3-methylene-2-pyrrolidone,
1-n-propyl-3-methylene-2-pyrrolidone,
1-n-propyl-5-methylene-2-pyrrolidone,
1-isopropyl-3-methylene-2-pyrrolidone,
1-isopropyl-5-methylene-2-pyrrolidone,
1-n-butyl-3-methylene-2-pyrrolidone,
1-tert-butyl-3-methylene-2-pyrrolidone, 2-hydroxyethylmethacrylate
(HEMA), 2-hydroxyethyl acrylate (HEA), hydroxypropyl acrylate,
hydroxypropyl methacrylate (HPMA), trimethylammonium 2-hydroxy
propylmethacrylate hydrochloride, aminopropyl methacrylate
hydrochloride, dimethylaminoethyl methacrylate (DMAEMA), glycerol
methacrylate (GMA), N-vinyl-2-pyrrolidone (NVP), allyl alcohol,
vinylpyridine, a C.sub.1-C.sub.4-alkoxy polyethylene
glycol(meth)acrylate having a weight average molecular weight of up
to 1500, methacrylic acid, N-vinyl formamide, N-vinyl acetamide,
N-vinyl isopropylamide, N-vinyl-N-methyl acetamide, N-vinyl
caprolactam, and mixtures thereof.
By incorporating a certain amount of hydrophobic vinylic monomer in
a fluid composition, the mechanical properties (e.g., modulus of
elasticity) of the resultant polymer may be improved. Nearly any
hydrophobic vinylic monomer can be used in the invention. Examples
of preferred hydrophobic vinylic monomers include
methyl(meth)acrylate, ethyl (meth)acrylate, propyl(meth)acrylate,
isopropyl(meth)acrylate, butyl(meth)acrylate, sec-butyl
meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate,
cyclohexylacrylate, 2-ethylhexylacrylate, vinyl acetate, vinyl
propionate, vinyl butyrate, vinyl valerate, styrene, chloroprene,
vinyl chloride, vinylidene chloride, acrylonitrile, 1-butene,
butadiene, methacrylonitrile, vinyl toluene, vinyl ethyl ether,
perfluorohexylethyl-thio-carbonyl-aminoethyl-methacrylate,
isobornyl methacrylate, trifluoroethyl methacrylate,
hexafluoro-isopropyl methacrylate, hexafluorobutyl methacrylate, a
siloxane-containing vinylic monomer as described previously, a
polysiloxane-containing vinylic monomer (having 3 to 8 silicone
atoms), and mixtures thereof. Most preferably, the polymerizable
composition comprises a bulky hydrophobic vinylic monomer.
Preferred bulky hydrophobic vinylic monomers include without
limitation N-[tris(trimethylsiloxy)silylpropyl](meth)acrylamide;
tris(trimethylsilyloxy)-silylpropyl methacrylate (TRIS);
(3-methacryloxy-2-hydroxypropyloxy)propyl-bis(trimethylsiloxy)-methylsila-
ne);
(3-methacryloxy-2-hydroxypropyloxy)propyl-tris(trimethylsiloxy)silane-
; cyclohexylacrylate, isobornyl methacrylate, a
polysiloxane-containing vinylic monomer (having 3 to 8 silicone
atoms), and combinations thereof.
Preferred polymerizable UV absorbing agents include without
limitation 2-(2-hydroxy-5-vinylphenyl)-2H-benzotriazole,
2-(2-hydroxy-5-acrylyloxyphenyl)-2H-benzotriazole,
2-(2-hydroxy-3-methacrylamido methyl-5-tert
octylphenyl)benzotriazole,
2-(2'-hydroxy-5'-methacrylamidophenyl)-5-chlorobenzotriazole,
2-(2'-hydroxy-5'-methacrylamidophenyl)-5-methoxybenzotriazole,
2-(2'-hydroxy-5'-methacryloxypropyl-3'-t-butyl-phenyl)-5-chlorobenzotriaz-
o le, 2-(2'-hydroxy-5'-methacryloxyethylphenyl)benzotriazole,
2-(2'-hydroxy-5'-methacryloxypropylphenyl)benzotriazole,
2-hydroxy-4-acryloxy alkoxy benzophenone, 2-hydroxy-4-methacryloxy
alkoxy benzophenone, allyl-2-hydroxybenzophenone,
2-hydroxy-4-methacryloxy benzophenone. A polymerizable UV-absorbing
agent is generally present in the polymerizable composition for
preparing a polysiloxane copolymer which is ethylenically
functionalized in turn to obtain a polysiloxane prepolymer of the
invention in an amount sufficient to render a contact lens, which
is made from a lens forming material including the prepolymer and
which absorbs at least about 80 percent of the UV light in the
range of from about 280 nm to about 370 nm that impinges on the
lens. A person skilled in the art will understand that the specific
amount of UV-absorbing agent used in the polymerizable composition
will depend on the molecular weight of the UV-absorbing agent and
its extinction coefficient in the range from about 280 to about 370
nm. In accordance with the invention, the polymerizable composition
comprises about 0.2% to about 5.0%, preferably about 0.3% to about
2.5%, more preferably about 0.5% to about 1.8%, by weight of a
UV-absorbing agent.
A photoinitiator can initiate free radical polymerization and/or
crosslinking by the use of light. Suitable photoinitiators are
benzoin methyl ether, diethoxyacetophenone, a benzoylphosphine
oxide, 1-hydroxycyclohexyl phenyl ketone and Darocur and Irgacure
types, preferably Darocur 1173.RTM., Irgacure 369.RTM., Irgacure
379.RTM., and Irgacure 2959.RTM.. Examples of benzoylphosphine
oxide initiators include 2,4,6-trimethylbenzoyldiphenylophosphine
oxide (TPO); bis-(2,6-dichlorobenzoyl)-4-N-propylphenylphosphine
oxide; and bis-(2,6-dichlorobenzoyl)-4-N-butylphenylphosphine
oxide. Reactive photoinitiators which can be incorporated, for
example, into a macromer or can be used as a special monomer are
also suitable. Examples of reactive photoinitiators are those
disclosed in EP 632 329, herein incorporated by reference in its
entirety. The polymerization can then be triggered off by actinic
radiation, for example light, in particular UV light of a suitable
wavelength. The spectral requirements can be controlled
accordingly, if appropriate, by addition of suitable
photosensitizers.
Cross-linking agents are compounds having two or more ethylenically
unsaturated groups and having a molecular weight of less than 700
Daltons. Crosslinking agents may be used to improve structural
integrity and mechanical strength. Examples of cross-linking agents
include without limitation tetra(ethyleneglycol) diacrylate,
tri(ethyleneglycol)diacrylate, ethyleneglycol diacylate,
di(ethyleneglycol)diacrylate, tetraethyleneglycol dimethacrylate,
triethyleneglycol dimethacrylate, ethyleneglycol dimethacylate,
di(ethyleneglycol)dimethacrylate, trimethylopropane
trimethacrylate, pentaerythritol tetramethacrylate, bisphenol A
dimethacrylate, vinyl methacrylate, ethylenediamine
dimethyacrylamide, glycerol dimethacrylate, triallyl isocyanurate,
triallyl cyanurate, allylmethacrylate, and combinations thereof. A
preferred cross-linking agent is tetra(ethyleneglycol)diacrylate,
tri(ethyleneglycol)diacrylate, ethyleneglycol diacrylate,
di(ethyleneglycol)diacrylate, triallyl isocyanurate, or triallyl
cyanurate.
The amount of a cross-linking agent used is expressed in the weight
content with respect to the total polymer and is preferably in the
range from about 0.05% to about 4%, and more preferably in the
range from about 0.1% to about 2%.
Examples of preferred pigments include any colorant permitted in
medical devices and approved by the FDA, such as D&C Blue No.
6, D&C Green No. 6, D&C Violet No. 2, carbazole violet,
certain copper complexes, certain chromium oxides, various iron
oxides, phthalocyanine green, phthalocyanine blue, titanium
dioxides, etc. See Marmiom DM Handbook of U.S. Colorants for a list
of colorants that may be used with the present invention. A more
preferred embodiment of a pigment include (C.I. is the color index
no.), without limitation, for a blue color, phthalocyanine blue
(pigment blue 15:3, C.I. 74160), cobalt blue (pigment blue 36, C.I.
77343), Toner cyan BG (Clariant), Permajet blue B2G (Clariant); for
a green color, phthalocyanine green (Pigment green 7, C.I. 74260)
and chromium sesquioxide; for yellow, red, brown and black colors,
various iron oxides; PR122, PY154, for violet, carbazole violet;
for black, Monolith black C-K (CIBA Specialty Chemicals).
The bioactive agent incorporated in the polymeric matrix is any
compound that can prevent a malady in the eye or reduce the
symptoms of an eye malady. The bioactive agent can be a drug, an
amino acid (e.g., taurine, glycine, etc.), a polypeptide, a
protein, a nucleic acid, or any combination thereof. Examples of
drugs useful herein include, but are not limited to, rebamipide,
ketotifen, olaptidine, cromoglycolate, cyclosporine, nedocromil,
levocabastine, lodoxamide, ketotifen, or the pharmaceutically
acceptable salt or ester thereof. Other examples of bioactive
agents include 2-pyrrolidone-5-carboxylic acid (PCA), alpha
hydroxyl acids (e.g., glycolic, lactic, malic, tartaric, mandelic
and citric acids and salts thereof, etc.), linoleic and gamma
linoleic acids, and vitamins (e.g., B5, A, B6, etc.).
Examples of leachable lubricants include without limitation
mucin-like materials (e.g., polyglycolic acid), non-crosllinkable
hydrophilic polymers (i.e., without ethylenically unsaturated
groups), one or more hydrophobic comfort agent, and a mixture
thereof.
Any hydrophilic polymers or copolymers without any ethylenically
unsaturated groups can be used as leachable lubricants. Preferred
examples of non-crosslinkable hydrophilic polymers include, but are
not limited to, polyvinyl alcohols (PVAs), polyamides, polyimides,
polylactone, a homopolymer of a vinyl lactam, a copolymer of at
least one vinyl lactam in the presence or in the absence of one or
more hydrophilic vinylic comonomers, a homopolymer of acrylamide or
methacrylamide, a copolymer of acrylamide or methacrylamide with
one or more hydrophilic vinylic monomers, polyethylene oxide (i.e.,
polyethylene glycol (PEG)), a polyoxyethylene derivative,
poly-N--N-dimethylacrylamide, polyacrylic acid, poly 2 ethyl
oxazoline, heparin polysaccharides, polysaccharides, and mixtures
thereof. The weight-average molecular weight M.sub.w of the
non-crosslinkable hydrophilic polymer is preferably from 5,000 to
1,500,000, more preferably from 50,000 to 1,200,000, even more
preferably from 100,000 to 1,000,000, Daltons.
A hydrophobic comfort agent is a compound or a mixture of compounds
which can strengthen and/or stabilize the tear film lipid layer.
Examples of hydrophobic comfort agents include, without limitation,
phospholipids, monoglycerides, diglycerides, triglycerides,
glycolipids, glyceroglycolipids, sphingolipids,
sphingo-glycolipids, fatty alcohols, hydrocarbons having a
C.sub.12-C.sub.28 chain in length, wax esters, fatty acids, mineral
oils, silicone oils, and combinations thereof.
Exemplary phospholipids include, without limitation, lecithin,
phosphatidyl ethanolamine, lysolecithin,
lysophosphatidylethanolamine, phosphatidylserine, phosphatidyl
inositol, sphingomyelin, cephalin, cardiolipin, phosphatidic acid,
cerebrosides, dicetyl-phosphate, phosphatidyl-choline and
dipalmitoyl-phosphatidylcholine. Preferred phospholipids are
phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine,
phosphatidylinositol, and sphingomyelin.
Glycolipids are carbohydrate-attached lipids. Exemplary glycolipids
include, without limitation, glyceroglycolipids,
glycosphingolipids, Gangliosides. Exemplary glyceroglycolipids
include, without limitation, Galactolipids, and Sulfolipids.
Glycosphingolipids are ceramides with one or more sugar residues
joined in a .beta.-glycosidic linkage at the 1-hydroxyl position.
Gangliosides have at least three sugars, one of which must be
sialic acid.
Exemplary sphingolipids include, without limitation,
sphingomyelins. Sphingomyelins have a phosphorylcholine or
phosphoroethanolamine molecule esterified to the 1-hydroxy group of
a ceramide.
Exemplary fatty alcohols include, without limitation, capryl
alcohol (1-octanol), 2-ethyl hexanol, pelargonic alcohol
(1-nonanol), capric alcohol (1-decanol, decyl alcohol), 1-dodecanol
(lauryl alcohol), myristyl alcohol (1-tetradecanol), cetyl alcohol
(1-hexadecanol), palmitoleyl alcohol (cis-9-hexadecen-1-ol),
stearyl alcohol (1-octadecanol), isostearyl alcohol
(16-methylheptadecan-1-ol), elaidyl alcohol (9E-octadecen-1-ol),
oleyl alcohol (cis-9-octadecen-1-ol), linoleyl alcohol
(9Z,12Z-octadecadien-1-ol), elaidolinoleyl alcohol (9E,
12E-octadecadien-1-ol), linolenyl alcohol
(9Z,12Z,15Z-octadecatrien-1-ol), elaidolinolenyl alcohol
(9E,12E,15-E-octadecatrien-1-ol), ricinoleyl alcohol
(12-hydroxy-9-octadecen-1-ol), arachidyl alcohol (1-eicosanol),
behenyl alcohol (1-docosanol), erucyl alcohol
(cis-13-docosen-1-ol), lignoceryl alcohol (1-tetracosanol), ceryl
alcohol (1-hexacosanol), montanyl alcohol, cluytyl alcohol
(1-octacosanol), myricyl alcohol, melissyl alcohol
(1-triacontanol), geddyl alcohol (1-tetratriacontanol), and
Cetearyl alcohol
Fatty acids can be medium chain fatty acids with alphatic tails of
8 to 14 carbons or long chain fatty acids with alphatic tails of at
least 16 carbons). The preferred fatty acids are long chain fatty
acids. Exemplary fatty acids include, without limitation, oleic
acid, stearic acid, palmytic acid myristic acid, linoleic acid,
linolenic acid, arachidic acid, arachadonic acid, myristoleic acid;
palmitoleic acid; oleic acid; .alpha.-linolenic acid;
eicosapentaenoic acid; erucic acid; docosahexaenoic acid.
A monoglyceride is a glyceride consisting of one fatty acid chain
covalently bonded to a glycerol molecule through an ester linkage,
and can be broadly divided into two groups; 1-monoacylglycerols and
2-monoacylglycerols, depending on the position of the ester bond on
the glycerol moiety. A diglyceride is a glyceride consisting of two
fatty acid chains covalently bonded to a glycerol molecule through
ester linkages. A triglyceride is glyceride in which the glycerol
is esterified with three fatty acids.
In accordance with the invention, a fluid composition can be a
solution or a melt at a temperature from about 20.degree. C. to
about 85.degree. C. Preferably, a fluid composition is a solution
of all desirable components in water, or an organic solvent, a
mixture of water and one or more organic solvents, or a mixture of
two or more organic solvents.
A fluid composition of the invention can be prepared by dissolving
all of the desirable components in any suitable solvent known to a
person skilled in the art. Example of suitable solvents includes
without limitation, water, tetrahydrofuran, tripropylene glycol
methyl ether, dipropylene glycol methyl ether, ethylene glycol
n-butyl ether, ketones (e.g., acetone, methyl ethyl ketone, etc.),
diethylene glycol n-butyl ether, diethylene glycol methyl ether,
ethylene glycol phenyl ether, propylene glycol methyl ether,
propylene glycol methyl ether acetate, dipropylene glycol methyl
ether acetate, propylene glycol n-propyl ether, dipropylene glycol
n-propyl ether, tripropylene glycol n-butyl ether, propylene glycol
n-butyl ether, dipropylene glycol n-butyl ether, tripropylene
glycol n-butyl ether, propylene glycol phenyl ether dipropylene
glycol dimetyl ether, polyethylene glycols, polypropylene glycols,
ethyl acetate, butyl acetate, amyl acetate, methyl lactate, ethyl
lactate, i-propyl lactate, methylene chloride, 2-butanol,
1-propanol, 2-propanol, menthol, cyclohexanol, cyclopentanol and
exonorborneol, 2-pentanol, 3-pentanol, 2-hexanol, 3-hexanol,
3-methyl-2-butanol, 2-heptanol, 2-octanol, 2-nonanol, 2-decanol,
3-octanol, norborneol, tert-butanol, tert-amyl, alcohol,
2-methyl-2-pentanol, 2,3-dimethyl-2-butanol, 3-methyl-3-pentanol,
1-methylcyclohexanol, 2-methyl-2-hexanol, 3,7-dimethyl-3-octanol,
1-chloro-2-methyl-2-propanol, 2-methyl-2-heptanol,
2-methyl-2-octanol, 2-2-methyl-2-nonanol, 2-methyl-2-decanol,
3-methyl-3-hexanol, 3-methyl-3-heptanol, 4-methyl-4-heptanol,
3-methyl-3-octanol, 4-methyl-4-octanol, 3-methyl-3-nonanol,
4-methyl-4-nonanol, 3-methyl-3-octanol, 3-ethyl-3-hexanol,
3-methyl-3-heptanol, 4-ethyl-4-heptanol, 4-propyl-4-heptanol,
4-isopropyl-4-heptanol, 2,4-dimethyl-2-pentanol,
1-methylcyclopentanol, 1-ethylcyclopentanol, 1-ethylcyclopentanol,
3-hydroxy-3-methyl-1-butene, 4-hydroxy-4-methyl-1-cyclopentanol,
2-phenyl-2-propanol, 2-methoxy-2-methyl-2-propanol
2,3,4-trimethyl-3-pentanol, 3,7-dimethyl-3-octanol,
2-phenyl-2-butanol, 2-methyl-1-phenyl-2-propanol and
3-ethyl-3-pentanol, 1-ethoxy-2-propanol, 1-methyl-2-propanol,
t-amyl alcohol, isopropanol, 1-methyl-2-pyrrolidone,
N,N-dimethylpropionamide, dimethyl formamide, dimethyl acetamide,
dimethyl propionamide, N-methyl pyrrolidinone, and mixtures
thereof.
In accordance with the invention, the monomer mixture can be
introduced (dispensed) into a cavity formed by a mold according to
any known methods.
After the monomer mixture is dispensed into the mold, it is
polymerized to produce a contact lens. Crosslinking may be
initiated by exposing the monomer mixture in the mold to a spatial
limitation of actinic radiation to crosslink the polymerizable
components in the monomer mixture. The crosslinking according to
the invention may be effected in a very short time, e.g. in
.ltoreq. about 200 seconds, preferably in .ltoreq. about 150
seconds, more preferably in .ltoreq.100 about seconds, even more
preferably in .ltoreq. about 50 seconds, and most preferably in 5
to 30 seconds.
Opening of the mold so that the molded lens can be removed from the
mold may take place in a manner known per se.
The molded contact lens can be subject to lens extraction to remove
unpolymerized polymerizable components, such as, for example,
vinylic monomers and/or macromers, crosslinkers, crosslinking
agents. The extraction solvent can be any solvent known to a person
skilled in the art. Examples of suitable extraction solvent are
those described above for preparing monomer mixtures. After
extraction, lenses can be hydrated in water or an aqueous solution
of a wetting agent (e.g., a hydrophilic polymer).
The molded contact lenses can further subject to further processes,
such as, for example, surface treatment (for example, such as,
plasma treatment, chemical treatments, the grafting of hydrophilic
monomers or macromers onto the surface of a lens, Layer-by-layer
coating, etc.); packaging in lens packages with a packaging
solution which can contain about 0.005% to about 5% by weight of a
wetting agent (e.g., a hydrophilic polymer described above) and/or
a viscosity-enhancing agent (e.g., methyl cellulose (MC), ethyl
cellulose, hydroxymethylcellulose, hydroxyethyl cellulose (HEC),
hydroxypropylcellulose (HPC), hydroxypropylmethyl cellulose (HPMC),
or a mixture thereof); sterilization; and the like.
The molded contact lenses preferably have at one property selected
from the group consisting of: an oxygen transmissibility (Dk/t) of
preferably at least about 50 barrers/mm, more preferably at least
about 60 barrers/mm, even more preferably at least about 80
barrers/mm; a lens center thickness of preferably from about 40
microns to 160 microns, more preferably from about 50 microns to
140 microns, even more preferably from about 60 microns to 120
microns; an elastic modulus of from about 0.1 MPa to about 2.0 MPa,
preferably from about 0.2 MPa to about 1.5 MPa, more preferably
from about 0.3 MPa to about 1.2, even more preferably from about
0.4 MPa to about 1.0 MPa; an Ionoflux Diffusion Coefficient, D, of,
preferably at least about 1.0.times.10.sup.-5 mm.sup.2/min, more
preferably at least about 2.0.times.10.sup.-5 mm.sup.2/min, even
more preferably at least about 6.0.times.10.sup.-5 mm.sup.2/min; a
water content of preferably from about 15% to about 65%, more
preferably from about 20% to about 55% by weight when fully
hydrated; and combinations thereof.
The invention is also related to silicone hydrogel contact lenses
made according to a method of the invention.
Although various embodiments of the invention have been described
using specific terms, devices, and methods, such description is for
illustrative purposes only. The words used are words of description
rather than of limitation. It is to be understood that changes and
variations may be made by those skilled in the art without
departing from the spirit or scope of the present invention, which
is set forth in the following claims. In addition, it should be
understood that aspects of the various embodiments may be
interchanged either in whole or in part or can be combined in any
manner and/or used together. Therefore, the spirit and scope of the
appended claims should not be limited to the description of the
preferred versions contained therein.
The previous disclosure will enable one having ordinary skill in
the art to practice the invention. In order to better enable the
reader to understand specific embodiments and the advantages
thereof, reference to the following non-limiting examples is
suggested. However, the following examples should not be read to
limit the scope of the invention.
EXAMPLE 1
Preparation of Chain-Extended Polydimethylsiloxane Vinylic Macromer
with Terminal Methacrylate Groups (CE-PDMS Macromer)
In the first step,
.alpha.,.omega.-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane
(Mn=2000, Shin-Etsu, KF-6001a) is capped with isophorone
diisocyanate by reacting 49.85 g of
.alpha.,.omega.-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane
with 11.1 g isophorone diisocyanate (IPDI) in 150 g of dry methyl
ethyl ketone (MEK) in the presence of 0.063 g of
dibutyltindilaurate (DBTDL). The reaction is kept for 4.5 h at
40.degree. C., forming IPDI-PDMS-IPDI. In the second step, a
mixture of 164.8 g of
.alpha.,.omega.-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane
(Mn=3000, Shin-Etsu, KF-6002) and 50 g of dry MEK are added
dropwise to the IPDI-PDMS-IPDI solution to which has been added an
additional 0.063 g of DBTDL. The reactor is held for 4.5 h at
40.degree. C., forming HO-PDMS-IPDI-PDMS-IPDI-PDMS-OH. MEK is then
removed under reduced pressure. In the third step, the terminal
hydroxyl-groups are capped with methacryloyloxyethyl groups in a
third step by addition of 7.77 g of isocyanatoethylmethacrylate
(IEM) and an additional 0.063 g of DBTDL, forming
IEM-PDMS-IPDI-PDMS-IPDI-PDMS-IEM.
Alternate Preparation of CE-PDMS Macromer with Terminal
Methacrylate Groups
240.43 g of KF-6001 is added into a 1-L reactor equipped with
stirring, thermometer, cryostat, dropping funnel, and
nitrogen/vacuum inlet adapter, and then dried by application of
high vacuum (2.times.10.sup.-2 mBar). Then, under an atmosphere of
dry nitrogen, 320 g of distilled MEK is then added into the reactor
and the mixture is stirred thoroughly. 0.235 g of DBTDL are added
to the reactor. After the reactor is warmed to 45.degree. C., 45.86
g of IPDI are added through an addition funnel over 10 minutes to
the reactor under moderate stirring. The reaction is kept for 2
hours at 60.degree. C. 630 g of KF-6002 dissolved in 452 g of
distilled MEK are then added and stirred until a homogeneous
solution is formed. 0.235 g of DBTDL are added, and the reactor is
held at 55.degree. C. overnight under a blanket of dry nitrogen.
The next day, MEK is removed by flash distillation. The reactor is
cooled and 22.7 g of IEM are then charged to the reactor followed
by 0.235 g of DBTDL. After 3 hours, an additional 3.3 g of IEM are
added and the reaction is allowed to proceed overnight. The
following day, the reaction mixture is cooled to 18.degree. C. to
obtain CE-PDMS macromer.
Lens Formulation
A lens formulation for cast-molding of silicone hydrogel contact
lenses are prepared to have the following composition: 33.0% by
weight of CE-PDMS prepared above; 17.0% by weight of
N-[tris(trimethylsiloxy)-silylpropyl]acrylamide (TRIS-acrylamide);
24.0% by weight of N,N-dimethylacrylamide (DMA); 0.5& by weight
of N-(carbonyl-methoxypolyethylene
glycol-2000)-1,2-disteaoyl-sn-glycero-3-phosphoethanolamin, sodium
salt) (L-PEG 2000); 1.0% by weight of Darocur 1173; 24.5% by weight
of 1-Propanol.
EXAMPLE 2
This example illustrates how to select a surfactant the aqueous
solution of which can be used to effectively wash the molding
surfaces of a reusable mold for cast-molding silicone hydrogel
contact lenses from a lens formulation prepared in Example 1.
Aqueous solutions of various surfactants are tested for their
efficacy in dissolving silicone-containing components of the lens
formulation prepared in Example 1 as follows. 10 ml of DI water is
measured into plastic vials. 1 drop (.about.20-40 mg) of a
surfactant is added to the water. Then 2 drops (.about.60-80 mg) of
CE-PDMS macromer prepared in Example 1 is added to this mixture.
The samples are observed before shaking and also after vigorous
shaking for their solubility in the surfactant solution. The
promising candidates are further screened by adding substituting
TRIS-acrylamide (40-50 mg) instead of CE-PDMS macromer.
The results of tests are reported in Table 1. Based on visual
observation, 4 surfactant solutions (Tetronic 1301, Silube Silwax
J-208 412, Sylgard 309, and BRIJ 30) can dissolve CE-PDMS macromer
and disperse TRIS-acrylamide to form a cloudy solution (believed to
be due to emulsification of TRIS-acrylamide).
TABLE-US-00001 TABLE 1 Solubility Surfactant CE-PDMS
TRIS-Acrylamide Tetronic 1301 Yes Yes * Tetronic 1307 Yes No
Tetronic 1107 Yes No Sulphur Dodecyl Sulphate Yes No Pluronic F127
Yes No Tetronic 304 Yes No Pluronic F68 PRILL Yes No Pluronic F87
PRILL Yes No BRIJ 30 Yes Yes * Sylgard 309 Silicone Surfactant
.sup.# Yes Yes * CMS-626 (Gelest) Yes No DBP-534 (Gelest) Yes No
DBP-814 (Gelest) Yes No DBP-821 (Gelest) Yes No DBP-732 (Gelest)
Yes No Silube J-208 412 Yes Yes * Silwax J-208 412 Yes No Siltech
Silwax J-208 212 Yes No * cloudy solution with small white
TRIS-acrylamide particles. .sup.# From Dow Corning.
The aqueous solutions of the following surfactants fail to dissolve
CE-PDMS in their tests: Pluronic F108NF, Tetronic 90R4; from
Siltech, Silwax J208 612, Silwax J208 812, Silwax J208 2 ume,
Silwax J208 4 ume, Silwax J208 6 ume, Silwax J208 8 ume; and from
Gelest, VDT-954, YRD-122, VDT-731, CMS-222, YBD-125, CMS-832.
Aqueous solutions of isopropanol (from 5% to 20% by weight) are
also tested with for their solubility of CE-PDMS and
TRIS-acrylamide. 10% and 5% IPA solution show progressive decrease
in the ability to dissolve CE-PDMS and TRIS with the 5% solution
showing poor solubility properties. 20% IPA solution is found to be
very effective in dissolving CE-PDMS into a cloudy emulsion and
completely dissolving TRIS-acrylamide.
EXAMPLE 3
Various percent ethylenically-functionalized polysiloxanes are
prepared as follows. KF-6001A
(.alpha.,.omega.-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane,
Mn=2000, from Shin-Etsu) and KF-6002A
(.alpha.,.omega.-bis(2-hydroxyethoxypropyl)-polydimethylsiloxane,
Mn=3400, from Shin-Etsu) are separately dried at about 60.degree.
C. for 12 hours (or overnight) under high vacuum in a single neck
flask. The OH molar equivalent weights of KF-6001A and KF-6002A are
determined by titration of hydroxyl groups and are used to
calculate the milimolar equivalent to be used in the synthesis.
A-1. Synthesis of Partially Ethylenically-Functionalized
Polysiloxanes
A one-liter reaction vessel is evacuated overnight to remove
moisture, and the vacuum broken with dry nitrogen. 75.00 g (75 meq)
of dried KF6001A is charged to the reactor, and then 16.68 g (150
meq) of freshly distilled isophorone diisocyanate (IPDI) is added
into the reactor. The reactor is purged with nitrogen and heated to
45.degree. C. with stirring and then 0.30 g of dibutyltin dilaurate
(DBTDL) is added. The reactor is sealed, and a positive flow of
nitrogen is maintained. An exotherm occurs, after which the
reaction mixture is allowed to cool and stir at 55.degree. C. for 2
hours. After reaching the exotherm, 248.00 g (150 meq) of dried
KF6002A is added to the reactor at 55.degree. C. and then 100 .mu.L
of DBTDL is added. The reactor is stirred for four hours. Heating
is discontinued and the reactor is allowed to cool overnight. The
nitrogen bubble is discontinued and the reactor is opened to
atmosphere for 30 minutes with moderate stirring. A
hydroxyl-terminated polysiloxane having 3 polysiloxane segments,
HO-PDMS-IPDI-PDMS-IPDI-PDMS-OH is formed.
For 80% ethylenically-functionalized polysiloxane, 18.64 g (120
meq) of isocyanatoethyl methacrylate (IEM) is added to the reactor,
along with 100 .mu.L of DBTDL. The reactor is stirred for 24 hours,
and then product is decanted and stored under refrigeration. For
preparation of various percentage of ethylenically
functionalization of a polysiloxane, various quantities of IEM are
applied according following Table 1.
TABLE-US-00002 TABLE 1 % Ethylenical Functionalization of
Polysiloxane Wt. of IEM A-1.1 60% 13.98 g (90 mEq) A-1.2 70% 16.31
g (105 meq) A-1.3 80% 18.64 g (120 meq) A-1.4 100% 23.30 g (150
meq)
A-2. 100% (Fully) Ethylenically Functionalized Polysiloxane:
A one-liter reaction vessel is evacuated overnight to remove
moisture, and the vacuum broken with dry nitrogen. 75.00 g (75 meq)
of dried KF6001A is charged to the reactor and dried at 60.degree.
C. under high vacuum for 8 hours, and then 23.30 g (150 meq) of IEM
is added to the reactor under nitrogen. After 30 minutes of
stirring, 0.2 g of DBTDL is added to the mixture. The reactor is
stirred at 25.+-.3.degree. C. for about 4 hours, and then product
is decanted and stored under refrigeration.
EXAMPLE 4
This example illustrates the effects of percentage of
ethylenically-functionalization of polydisloxane, which is used to
prepare a prepolymer that in turn is used to prepare lens
formulation, upon the viscosities of the lens formulations.
B-1. Synthesis of Amphiphilic Branched Copolymer
A 1-L jacketed reactor is equipped with 500-mL addition funnel,
overhead stirring, reflux condenser with nitrogen/vacuum inlet
adapter, thermometer, and sampling adapter. 48.55 g of partially
ethylenically-functionalized polysiloxane (PDMS) prepared in
Example 3, A-1.1 is charged to the reaction vessel. The PDMS A-1.1
is degassed under vacuum less than 1 mbar at room temperature for
30 minutes. After the degassed is accomplished, the reactor is
filled with nitrogen gas waiting for further process. The monomer
solution composed of 26.06 g of N,N-dimethylacrylamide (DMA), 23.14
g of (tris(trimethylsilyl))siloxypropyl)-methacrylamide (TRIS-Am),
and 350 g of ethyl acetate is charged to the 500-mL addition funnel
followed with a degas under vacuum 100 mbar at room temperature for
10 minutes and then refilled with nitrogen gas. The monomer
solution is degassed with same conditions for additional two
cycles. The monomer solution is then charged to the reactor. The
reaction mixture is heated to 64.degree. C. with stirring. While
heating, a solution composed of 1.75 g of mercaptoethanol (chain
transfer agent, CTA) and 0.30 g of azoisobutyronitrile (Initiator)
and 50 g of ethyl acetate is charged to the addition funnel
followed by same degassing process as the monomer solution. When
the reactor temperature reaches 64.degree. C., the initiator/CTA
solution is also added to reactor. The reaction is performed at
64.degree. C. for 6 hours. After the copolymerization is completed,
reactor temperature is cooled to room temperature.
B-2. Synthesis of Amphiphilic Branched Prepolymer
The copolymer solution prepared above (B-1) is ethylenically
functionalized to form an amphiphilic branched prepolymer by adding
4.52 g of IEM (or an amount shown in Table 2) and 0.15 g of DBTDL.
The mixture is stirred at room temperature under a sealed condition
for 12 hours. The prepared prepolymer is then stabilized with 100
ppm of hydroxyl-tetramethylene piperonyloxy. After the reaction
solvent is exchanged to 1-propanol, the solution is ready to be
used for formulation. Various amphiphilic branched prepolymers are
prepared with various combination of various %
ethylenically-functionalized polysiloxane, CTA levels and IEM as
indicated in Table 2.
TABLE-US-00003 TABLE 2 Amphiphilic Branched %
ethylenically-functionalized Prepolymer polysiloxane CTA % IEM B-2a
Example 3, A-1.1 (60%) 1.75% 4.52 g B-2b Example 3, A-1.2 (70%
1.75% 4.35 g B-2c Example 3, A-1.3 (80%) 1.75% 4.17 g B-2d Example
3, A-1.4 (100%) 1.75% 3.83 g B-2e Example 3, A-1.1 (60%) 1.25% 3.43
g B-2f Example 3, A-1.2 (70% 1.25% 3.25 g B-2g Example 3, A-1.3
(80%) 1.25% 3.08 g
B-3: Preparation of Lens Formulations
Lens formulations are prepared by dissolving an amphiphilic
branched prepolymer prepared above (B-2a to B-2g) and other
components shown in Table 3. Other ingredients in each formulation
include 1.0% of DC1171, 0.75% of DMPC and 23.25% of 1-PrOH.
Photorheologys of the prepared lens formulations are cured by UV
with an intensity of 16 mW/cm.sup.2 with 330 nm filter and also
summarized in Table 3.
TABLE-US-00004 TABLE 3 Lens Formulation Photorheology Amphiphilic
Curing Branched Time, G' Viscosity Prepolymer DMA TRIS-Am* seconds
kPa mPa s 65% of B-2a 5.3% 4.7% 19 90 1020 65% of B-2b 5.3% 4.7% 17
100 1850 65% of B-2c 5.3% 4.7% 16 110 2720 65% of B-2d 5.3% 4.7% 16
90 3150 65% of B-2e 5.3% 4.7% 15 100 2100 65% of B-2f 5.3% 4.7% 14
105 3280 65% of B-2g 5.3% 4.7% 16 105 5900
*(tris(trimethylsilyl))siloxypropyl)-acrylamide (TRIS-Am)
EXAMPLE 5
C-1: Synthesis of Amphiphilic Branched Copolymer
A 4-L jacketed reactor is equipped with overhead stirring, reflux
condenser with nitrogen/vacuum inlet adapter, thermometer, and
sampling adapter. A mixture of 78.35 g of partially
ethylenically-functionalized polysiloxane prepared in Example 3,
A-1.3 and 8.71 g of Example 3, A-2 is charged to the 4-L reactor
and then degassed under vacuum less than 10 mbar at room
temperature for 30 minutes. After the degassing, the reactor is
filled with nitrogen gas waiting for further process. The monomer
solution composed of 52.51 g of DMA, 56.65 g of TRIS-Am and 390 g
of cyclohexane is transferred to the reactor. The final mixture is
degassed at 100 mbar for 5 minutes and then refilled with nitrogen
gas. This degas cycle is repeated for 4 more times. The reaction
mixture is then heated to 64.degree. C. followed by adding a
degassed initiator/CTA solution composed of 0.60 g of V-601, 7.50 g
of mercaptoethanol and 10 g of THF. The copolymerization is
performed at 64.degree. C. under nitrogen for totally 6 hours.
After reaction is finished, reactor temperature is cooled to room
temperature.
C-2. Synthesis of Amiphiphilic Branched Prepolymer
The copolymer solution prepared above (C-1) is ethylenically
functionalized to form an amphiphilic branched prepolymer by adding
7.50 g of IEM and 0.21 g of DBTDL, followed by an agitation under a
sealed dry condition at room temperature for 48 hours. The prepared
prepolymer is then stabilized with 100 ppm of
hydroxy-tetramethylene piperonyloxy. After the reaction solvent is
exchanged to 1-propanol, the solution is ready to be used for
formulation.
C-3: Preparation of Lens Formulations and Photorheology
The amphiphilic branched prepolymer prepared above (C-3) is
formulated with final compositions listed in Table 4. Photorheology
of prepared formulations are cured by UV with intensity 16
mW/cm.sup.2 with 330 nm filter.
TABLE-US-00005 TABLE 4 Photorheology Formulation Curing G'
Viscosity Lot# C-2 DMA DC1173 DMPC 1-PrOH Time (s) kPa mPa s C-3.1
69% 6% 1.0% 0.75% 23.25% 19 115 3200 C-3.2 70% 5% 1.0% 0.75% 23.25%
21 114 3400 DMPC: 1,2-dimyristoyl-sn-glycero-3-phosphocholine;
DC1173: Darocur 1173
EXAMPLE 6
D-1. Synthesis of Amphiphilic Branched Copolymer
A 1-L jacketed reactor is equipped with 500-mL addition funnel,
overhead stirring, reflux condenser with nitrogen/vacuum inlet
adapter, thermometer, and sampling adapter. 45.60 g of partially
ethylenically-functionalized polysiloxane prepared in Example 3,
A-1.3 is charged to the reaction vessel and then degassed under
vacuum less than 1 mbar at room temperature for 30 minutes. After
the degassing, reactor is filled with nitrogen gas waiting for
further process. The monomer solution composed of 0.65 g of
hydroxyethyl methacrylate (HEMA), 25.80 g of DMA, 27.80 g of
3-[Tris(trimethylsiloxy)silyl]propyl methacrylate (TRIS), and 279 g
of ethyl acetate is charged to the 500-mL addition funnel followed
with a degas under vacuum 100 mbar at room temperature for 10
minutes and then refilled with nitrogen gas. The monomer solution
is degassed with same conditions for additional two cycles. The
monomer solution is then charged to the reactor. The reaction
mixture is heated to 67.degree. C. with stirring. While heating, a
solution composed of 1.50 g of mercaptoethanol (CTA) and 0.26 g of
azoisobutyronitrile(initiator) and 39 g of ethyl acetate is charged
to the addition funnel followed by same degas process as the
monomer solution. When the reactor temperature reaches 67.degree.
C., the initiator/CTA solution is also added to reactor. The
reaction is performed at 67.degree. C. for 8 hours. After the
copolymerization is completed, reactor temperature is cooled to
room temperature.
D-2. Synthesis of Amiphiphilic Branched Prepolymer
The copolymer solution prepared above (D-1) is ethylenically
functionalized to form an amphiphilic branched prepolymer by adding
4.45 g of IEM in the presence of 0.21 g of DBTDL. The mixture is
stirred at room temperature under a sealed condition for 24 hours.
The prepared macromonomer is then stabilized with 100 ppm of
hydroxy-tetramethylene piperonyloxy before the solution is
concentrated to 200 g (.about.50%) and filtered through 1 um pore
size filter paper. The solid content is measured via removing the
solvent at vacuum oven at 80.degree. C. After the reaction solvent
is exchanged to 1-propanol, the solution is further concentrated to
the desired concentration and ready to be used for preparing lens
formulations.
It is understood that isocyanatoethyl acrylate can be replaced with
isocyanatoethyl methacrylate to prepare UV-absorbing prepolymer
containing methacrylate groups.
D-3. Preparation of Lens Formulation and Photorheology
A lens formulation is prepared to have the following composition:
72% by weight of prepolymer D2 prepared above; 6% by weight of DMA;
1% by weight of DC1173; 0.75% by weight of DMPC; and 20.25% by
weight of 1-PrOH. Photo-rheology is studied by using the Hamamatsu
lamp with a 330 nm long pass cutoff filter placed just before the
sample. The intensity (16 mW/cm.sup.2) is measured by using an
IL1700 detector using a SED005 sensor with a 297 nm cutoff filter
from International light, the long pass filters are place before
the sample for curing the formulation. The results of photorheology
study are: a curing time of about 12 seconds, G' of 165 kPa, and a
viscosity of 5550 mPas.
EXAMPLE 7
E-1: Synthesis of UV-absorbing Amphiphilic Branched Copolymer
A 1-L jacketed reactor is equipped with 500-mL addition funnel,
overhead stirring, reflux condenser with nitrogen/vacuum inlet
adapter, thermometer, and sampling adapter. 45.98 g of partially
ethylenically functionalized polysiloxane prepared in Example 3,
A-1.3 is charged to the reaction flask and then degassed under
vacuum less than 1 mbar at room tempertaure for 30 minutes. The
monomer solution prepared by mixing 0.51 g of HEMA, 25.35 g of DMA,
1.38 g of Norbloc methacrylate, 26.03 g of TRIS, and 263 g of ethyl
acetate is charged to the 500-mL addition funnel followed with a
degas under vacuum 100 mbar at room temperature for 10 minutes and
then refilled with nitrogen gas. The monomer solution is degassed
with same conditions for additional two cycles. The monomer
solution is then charged to the reactor. The reaction mixture is
heated to 67.degree. C. with adequate stirring. While heating, a
solution composed of 1.48 g of mercaptoethanol (chain transfer
agent, CTA) and 0.26 g of azoisobutyronitrile(initiator) and 38 g
of ethyl acetate is charged to the addition funnel followed by same
degas process as the monomer solution. When the reactor temperature
reaches 67.degree. C., the initiator/CTA solution is also added to
reactor. The reaction is performed at 67.degree. C. for 8 hours.
After the copolymerization is completed, reactor temperature is
cooled to room temperature.
E-2: Synthesis of UV-Absorbing Amphiphilic Branched Prepolymer
The copolymer solution prepared above (E-1) is ethylenically
functionalized to form an amphiphilic branched prepolymer by adding
3.84 g of IEM in the presence of 0.15 g of DBTDL. The mixture is
stirred at room temperature under a sealed condition for 24 hours.
The prepared prepolymer is then stabilized with 100 ppm of
hydroxy-tetramethylene piperonyloxy before the solution is
concentrated to 200 g (.about.50%) and filtered through 1 um pore
size filter paper. After the reaction solvent is exchanged to
1-propanol, the solution is ready to be used for formulation. The
solid content is measured via removing the solvent at vacuum oven
at 80.degree. C.
It is understood that isocyanatoethyl acrylate can be replaced with
isocyanatoethyl methacrylate to prepare UV-absorbing prepolymer
containing methacrylate groups.
E-3: Preparation of Lens Formulation and Photorheology
A lens formulation is prepared to have the following composition:
71% by weight of prepolymer E2 prepared above; 4% by weight of DMA;
1% by weight of TPO; 0.75% by weight of DMPC; and 23.25% by weight
of 1-PrOH. Photo-rheology is studied by using the Hamamatsu lamp
with a stack of 330 nm and 388 nm long pass cutoff filters placed
just before the sample. The intensity (4.6 mW/cm.sup.2) is measured
by using an IL1700 detector using a SED005 sensor with a 297 nm
cutoff filter from International light, the long pass filters are
place before the sample for curing the formulation. The results of
photorheology study are: a curing time of about 22 seconds, G' of
155 kPa, and a viscosity of 2900 mPas.
EXAMPLE 8
Cast Molding of Silicone Hydrogel Lenses under a Spatial Limitation
of Actinic Radiation
Lenses are prepared by cast-molding of a lens formulation prepared
in one of Examples 1 and 5-7 in a reusable mold, similar to the
mold shown in FIGS. 1-6 in U.S. Pat. Nos. 7,384,590 and 7,387,759
(FIGS. 1-6). The mold comprises a female (front curve) mold half
made of glass and a male (base curve) mold half made of V38 quartz.
The UV irradiation source is a Hamamatsu lamp with the WG335+TM297
cut off filter at an intensity of about 4 mW/cm.sup.2. The lens
formulation in the mold is irradiated with UV irradition for about
28 seconds. After opening the mold and removing the molded lens
from the mold, the molding surfaces of the male (base curve) and
female (front curve) mold halves are washed as described below.
Cleaning and Foaming Characteristics of Mold Cleaning Aqueous
Solutions
The foaming properties of mold cleaning solutions have been
determined. A mold cleaning solution containing 0.714% by weight of
Silsurf B208 can have a foam height of about 26 mm when the mold
solution is used in dispensing tank equipped with re-circulating
pump with the pump on for about 7 minutes and maintained at
40.degree. C. and is spread on mold surface at a nozzle to mold
edge distance of about 1.0 cm and about 50 psi with a 65.degree.
fan spread nozzle with 25.degree. spread angle. When about 0.1429%
of defoamer KM-7750B from ShinEtsu is added to the mold cleaning
solution above and under the identical experimental conditions, a
foam height of about 1 mm is achieved. It is found that foaming of
a mold cleaning solution containing 0.714% by weight of Silsurf
B208 is manageable (a foam height of less than about 3 mm) in the
presence of about 0.0357% by weight of defoamer KM-7750B from Shin
Etsu when pump and nozzle are used intermittently
(non-continuously) and that 0.1429% of defoamer KM-7750B from
ShinEtsu can be used to suppress spread foam of a mold cleaning
solution containing 0.714% by weight of Silsurf B208 from SilTech
when pump and nozzle are used continuously.
BASF DF 10P MOD 12 defoamer has limited defoaming property because
even when it is present in an amount of about 0.28% by weight, the
foam height is about 7 mm under the testing conditions described
above.
Silsurf A208, lower molecular weight version of Silsurf B208, is
also has same cleaning capability as B208 with higher foaming
property. Higher concentration (about 0.22% of defoamer KM-7750B
from ShinEtsu is required to suppress spread foam of the mold
cleaning solution containing 0.714% by weight of Silsurf A208.
Silsurf C208 and B608, higher molecular weight version of B208,
have no cleaning capability. ShinEtsu KF-643 has limited cleaning
capability with very high foaming property. ShinEtsu KF-6011 and
F-518 have no cleaning capability. 1% Wilbur-Ellis Sylgard 309 is
able to clean off Nelsee formulation@50.degree. C. with high
foaming problem.
Mold Cleaning
A water based mold cleaning solution is prepared by mixing about
100 ml of Silsurf.RTM. B208 (from SilTech), about 20 ml of KM-7750B
defoamer (from Shin Etsu), and about 1.4 gm of NaHCO.sub.3 with
about 14 liters of DI water. Overhead mixer is used to agitate the
mold cleaning solution for about 10 minutes prior to use.
About 12 liters of the mold solution is used in dispensing tank
equipped with re-circulating pump and maintained at 40.degree.
C.
A 65.degree. fan spread nozzle with 0.degree. tilt angle in a first
washer with re-circulated mold cleaning solution at 40.degree. C.
is used to wash front curve (FC) and base curve (BC) molds for
about 30 seconds. About 2,025 ml of re-circulated mold cleaning
solution at 40.degree. C. is spread on mold surface at .about.50
psi then returned to dispensing tank. Nozzle to mold edge distance
is .about.0.8 cm for FC mold and .about.0.4 cm for BC mold.
A 65.degree. fan spread nozzle with .about.30.degree. tilt angle in
a second washer with 40.degree. C. fresh DI water is used to rinse
the washed FC and BC molds for about 20 seconds. About 1,350 ml of
40.degree. C. fresh DI water is spread on mold surface at .about.50
psi. Nozzle to mold edge distance is .about.1.3 cm for FC mold and
.about.0.4 cm for BC mold.
A multi-channel flat fan nozzle with 10.degree. tilt angle in a
third washer with nitrogen is used to dry FC and BC molds for about
7 seconds at 80 psi. Nozzle to mold edge distance is .about.1.0 cm
for FC mold and .about.0.5 cm for BC mold.
During the operations (washing, rinsing, and drying) described
above, mold holder (for FC and BC molds) is turning at 6 seconds
per rotation.
The molds are inspected with 40.times. stereo zoom microscope at
the end of the testing days to ensure the mold cleanness. It is
found that the 40.degree. C. re-circulated mold cleaning aqueous
solution prepared above is capable to clean off residues of the
various silicone hydrogel lens formulations tested from molds which
have been used to cast mold silicone hydrogel contact lenses from
the silicone hydrogel lens formulations.
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